The Multiclass System is a roleplaying game that allows characters to quickly accumulate a wide variety of abilities. Rather than utilizing a robust skill system, however, the game instead uses Classes but allows characters to engage simultaneously in multiple classes without penalty. Most of the rules are light-weight to streamline play. Most rules apply only to a single (or a few) class.

Characters begin with three Classes, each of which enables access to some class-specific Skills. Skill use, in all but trivial cases, requires a 3d6 roll below the Skill Rating. Situational modifiers may apply. Characters have a single "Stat" that functions like a universal Skill--if no Skill applies to a situation, characters roll against their "Stat".